This invention relates to the production of sulfur, and in particular to the production of sulfur from SO.sub.2 -containing gases.
SO.sub.2 -containing gases, especially those having an SO.sub.2 -content of 5 and of 95% by volume, are obtained in the chemical and petrochemical industries. They are also found in operation of the flue-gas desulfurizing installations of power-generating stations and in sintering installations. The other components of these gases are usually SO.sub.2, N.sub.2 and water vapor. As a rule, these gases are treated to recover their SO.sub.2 content as sulfur.
For this purpose it is known to contact SO.sub.2 -containing gases with other gases having a reduction effect, in the 900.degree.-1150.degree. C. temperature range, so as to obtain a gas mixture in which H.sub.2 S and SO.sub.2 are present in a ratio of 2:1. The thus obtained gas mixture is then converted according to the Claus process to obtain sulfur. Using a three-stage Claus system, it is possible to recover up to 94% of the SO.sub.2 in form of sulfur. However, this process requires the use of large quantities of reduction gases which are often not, or not readily, available.
Another known process is to reduce SO.sub.2 -containing gases to sulfur with the use of anthracite. This eliminates the need for reduction gases but has the disadvantage that the SO.sub.2 is reduced to sulfur only up to about 75%.